5) Pulmonary Dynamics

Question 1

Ventilatory Breakpoint

Answer 1

Point where VE and VCO2 incr disproportionately w/ VO2 during graded exercise

• aka anaerobic threshold (55% of VO2max)

Question 2

Lactate Threshold

Answer 2

The highest VO2 or exercise intensity before a 1.0mM incr in blood lactate concentration above resting

Question 3

How is VT measured?

Answer 3

Non-invasively through a metabolic cart

Question 4

How is lactate threshold measured?

Answer 4

Invasively through blood work

Question 5

What does cigarette smoking do to HR during exercise and why?

Answer 5

Blunts HR response → Alters sensitivity of autonomic neural control

Question 6

Desribe the energetic cost of breathing in pt’s w/COPD

Answer 6

• Normal cost of breathing at rest is tripled bc of respiratory resistance
  
  • Severely limits the exercise capacity

Question 7

What percentage of total exercise VO2 does energetic cost of breathing equal in pt’s w/COPD?

Answer 7

40%

Question 8

For pt’s w/COPD how can exercise training change PFT?

Answer 8

Small Improvements, however it can still:

• Incr exercise capacity
• Improve respiratory fxn
• Improve peripheral muscle fxn
• Decr dyspnea

Question 9

At rest, what controls the respiratory cycle?

Answer 9

Automatic activity of inspiratory neurons → Cell bodies in the medulla respond to incr in paCO2 and H+

Question 10

Is inspiration active or passive?

Answer 10

Active

Question 11

At rest, what regulates pulmonary ventilation?

Answer 11

Chemical state of blood

Question 12

Describe the process that occurs for the body to incr ventilation

Answer 12

1. Decr O2 stims peripheral chemoreceptors
2. Aortic and carotid chemoreceptors react to icnr ventilation

Question 13

Should paO2 decr in a healthy person?

Answer 13

No

Question 14

Besides reduced O2 pressures, what else do peripheral chemoreceptors incr ventilation in response to?

Answer 14

• Incr paCO2
• Incr temp
• Low BP
• Metabolic acidosis
• Changes in H+
• Exercise

Question 15

What is the most important stimulus for a healthy person at rest and why?

Answer 15

paCO2 → Small incr in paCO2 can cause a large incr in VE

Question 16

What stims pt’s w/COPD to breath

Answer 16

Hypoxic Drive (Low O2)

Question 17

What is the most stressful physiologic activity

Answer 17

Coughing

Question 18

Why does alveolar ventilation incr?

Answer 18

To maintain proper gas concentrations for rapid gas exchange

Question 19

Describe ventilatory, VO2, and VCO2 pattern during light and moderate exercise

Answer 19

Incr linearly

Question 20

For every L of consumed O2, how much air are we taking in?

Answer 20

20-25L

Question 21

Ventilatory Equivalent

Answer 21

VE:VO2 ratio

• Should be 25:1 during submax exercise (up to 55% of VO2max)

Question 22

Onset of Blood Lactate Accumulation (OBLA)

Answer 22

The exercise level when LA starts to systemically incr above resting level (4.0mM)

• Relates to onset of anaerobiosis and the subsequent accumulation of LA
• The more muscle mass used, the high the VO2 OBLA will occur at

Question 23

At OBLA, what process supplies energy?

Answer 23

Glycolysis

Question 24

What percent of VO2max does OBLA occur at in untrained and trained individuals?

Answer 24

• Untrained = 55-65%
• Trained = >70%

Question 25

What buffers LA during anaerobic metabolism and what are the byproducts? How do we get rid of these byproducts and why?

Answer 25

• Buffer = Sodium Bicarb
• Byproducts = Sodium Lactate, CO2, and H20
• Rid = Exhale → Creates too acidic of an environment for enzymes to fxn

Question 26

What factors determine OBLA?

Answer 26

• Recruited muscle fiber types
• # and size of mitochondria
• Changes in muscular enzymatic and oxidative capabilities
• Capillary density

Question 27

What factors determine VO2max?

Answer 27

• Absolute quantity of recruited muscle mass
• Fxnl capacity of CV system

Question 28

True or False: Changes in endurance performance as a result of training are more closely related to OBLA than VO2max?

Answer 28

True

Question 29

For most people, is ventilation a limiting factor of aerobic performance?

Answer 29

No

Question 30

What is a powerful predictor of aerobic performance?

Answer 30

Intensity of exercise at OBLA